Trunk circuits



June 7 1927 G. H. PETERSON TRUNK CIRCUITS Filed Feb. 25.v 1926 msm@ #Wen/0r.' 66a/ e/z Pe/ersm by 'c Patented June 7, 1927.

UNITED STATES GEORGE 1I. PETERSON, or Ensfr ORANGE', n EW ;JERsEr, -iissIefnoR To AMERICAN i i ,TELElONE ,AND www??? @10131343551 C93P0R'f101 ,0F ,NEW YORK# i ,TRUNK 'cIRcUITs Application filed February This invention relates gto telephone ex change systems in which connecting operators employed for .extending connections, -f

operators position, in the manual office, is

provided with `call' indicator mechanism,- including a set of number indicating devices, which is operated automatically under the control ofI registering mechanism in the mechanical office, to linform the manual operator of the number land character of the required connection. It is customary, in arrangements .of'this character, to provide each trunk circuit incoming toan operator-sposition fromthe distant mechanical oflice with a signal lamp, the illumination' of which advises the operator that a call is awaiting her attention von the correspond# ing trunk. At her convenience sheassociates the calling trunk with the commonvindi'cating mechanism at her position, and thereupon the wanted designation is set up and displayed before the operator, who proceeds to complete the connection.

There no attempt is made to secure a uni;

formity in the kdistribution of the calls tov the several operators in an office of this character, it'may frequently occur during' busy hours of the day, that an excessive number of calls simultaneously appear on the trunks of any given ,operators position, while at a position adjacent thereto only a comparatively few calls are awaiting attention. lIn order ythat the completion of calls shall not be unduly delayed on this account, provision is made whereby an operator adjacent to a home operators position may assist the home operator by attending to some of the calls at her position. j

In systems of this character it kmay tur-y ther V:be undesirable because of cost to extendl direct Atrunks from each office having mewhere certain offices areY 25, 1926. Serial Nvo. 90,644.

.chanicalswitching apparatus to each manual vterminating office. In such a case,vtandem offices are provided kwhich .are directly accessible from originating mechanical oiices, at. which tandemvoflices are located operators positions equipped with vnumber indieatingv devices. These operators, in turn, trunk desired yc onnections to terminating manual olices in which subscribers lines, the numbers of which are indicated on t-he number indicating mechanism, terminate. It thenf becomes necessary for the tandem operator .to converse with the terminating manual opera-tor to inform her of the de- Sired line number. It is desirable that this -bexdone over the established connection bel,tweenthe operators positions. without the knowledge of ther calling subscriber, and this `is done by splitting the trunk at the tandem ,position and connecting the tandem opera- -tors telephone circuit to the calling end of theV trunk circuit at her position.

Whereprovision is mad-e to enable an operator at a position, adjacent to the home position on which a call is incoming from a mechanical office, to attend to calls yat the home position, it is necessary uponsplitting the tru-nk circuit to connect the adjacent operators telephone circuit to the trunk kcrcuit rather than the home operators telephone circuit.`

ltis therefore the object of this invention to provide means for automatically splitting .the incoming 'trunk circuit Vwhen it is plugged up lto a trunk 'circuit outgoing to a terminating office, and for connecting the ltelephone circuit'of v.the home or adjacent operator to the calling end of the trunk circuit dependent upon which operator has responded to the call.

The invention isillustrated in the accompanying drawing, wherein a calling subscribersline is shown at the left of the' drawing, terminating in an ofiice X equipped with mechanical switching apparatus, and at the right of the drawing a called'subscribersline terminating in the manual office Cir Z, connection being extended betweena the offices 'X and Z through a manual tandem office Y. Y

To simplify the'disclosure the line lswitch 1, district selector 2 land sender 3 of the mechanical office X have been vonly 'diagrammatically illustrated.` For a fulldisclosure cent operators positions, which may be connected to all of the incoming trunk Circuits of these positions, have been illustrated by 1 small rectangles in the lower portion of the 'drawing This indicator mechanism may be of the type disclosed in the patent to A. E. Lundell'and E. H. Clark No. 1,464,084, issued August 7, 1923.

The B operators equipment shown in outline at oi'ice 'Z is fully disclosed in a copending application Serial No. 738,488, filed September 18, 1924, in the name` of R. S.-

Bailey'and E. P. Bree and a complete disclosure thereof herein is deemed unnecessary. It is tl'iought that the invention may be best understood from a description ot the manner in which a call is extended from substation A in oii'ice X to the substation B in ofliee Z. Upon the removal of the receiver at substation A, the line switch 1 functions in the usual manner to select an idle district selector 2, and thereupon an idle sender, suchvas 3, becomes associated with the calling line, The calling subscriber then manipulates his calling dial 4 in accordance with the oiiice and numerical designation of the desired line, whereupon the registers of the sender function in the usual manner to register the full line designation. Following the registration o the oice portion of the designation, the sender operates to set the district selector 2 upon a group of trunks extending to the tandem oiiice Y, through which access to the desired terminating oiiice Z may be obtained. The selector 2 then proceeds to hunt for and seize'an idle trunk 5 extending to such tandem oiiice Y.

When the connection' is 'extended to the trunk 5, a circuit is established for the r'e- ,lay 6 of the trunk 5, which may be traced in part from battery through the right winding of relay 6, the left back Contact of relay 7, the upper winding of impedance coil 10, conductor 50, the upper back contacts of relays 8 and 9, thence through the selector 2 and the sender 3, returning through the lower back Contacts of relays 8 and 9, conductor 51, the lower winding of coil 10, the right back contact of relay 7 to ground through the left winding oi relay 6. Relay 6 energizes in this circuit and establishes a circuit for relay 12, which may be traced from battery, through the outer right back contact ot' relay 13, winding of relay 12, inner right back contact of relay 11 to ground at the contact ot relay 6. Relay 12, upon energizing, 4closes. a locking circuit Jfor itself independent of the contact otrelay 13, which extends from battery through the inner right contact of relay 12, and thence to ground as traced at the contact of relay 6. At its outer right contact relay 12 establishes a circuit for lamp 14, from ground through auxiliary battery at control circuit 18, over conductor 22, the lett contact of relay 21, conductor 20, the right winding of relay 17, the inner left contact of relay 12, upper contact of key 16, conductor 19, to ground at the control circuit 18. Relay 17 operating in this circuit locks directly to ground through both ot its windings and its inner left contact, independently of key 16, and at its right contact closes an obvious circuit for relay 13. At its outer left contact,it prepares a circuit for relay 9. Relay V13, upon energizing, opens at its outer right contact the initial energizing circuit of relay 12, and closes at its inner right front contact a circuit for relay 23, which may be traced from battery, through the'inner right contact of relay 12, the inner right front Contact of relay 13, conductor 25, to ground through the winding of relay 23. Relay 23, upon energizing, extends conductor 25 through its inner right contact over conductor 24 through the winding of relay 11 to battery, thus placing the windings of relays 23 and 11 in series, b-ut relay 11 cannot operate so long as battery is connected to conductor 25 at the inner right contact of relay 12.

`With relays 17 and 23 both energized, a circuit is now effective for energizing relay 9 which may be traced from battery at the left contact of relay 23, over conductors 26 and 27, winding of relay 9, conductor 28, outer left contact of relay 17, conductor 36 t-o ground at the control circuit 18. The operation of relay 9 severs the incoming trunk conductors from the windings of relay 6, and connects these conductors over the front contacts of relay 9 and conductors 29 and 30to the cont-rol circuit 18, thereby causing such an operation of the senderas to initiate the transmission ot impulses to the control circuit 18 inl accordance with the registrations recorded in the sender, to record the line designation in the control circuit 18 in the well-known manner4 -The opening of the circuit of relay 6 by the operation of relay 9 causes the release of relay 6, and in turn, the release of relay 12. Relay12, upon releasing, removes battery at its inner'right contact from the conductor 25, thereby permitting relay `1l t9 4lOfCQIrle lllil lamp 14, resistance 15, outer right back conV tact of relay 12, conductor 31, lett front contact of relay 13, conductor o2, left back contact ot' relay 33, interrupter 34 to ground. Lamp 14 theniiashes as van indication to the operator that the call incoming on trunk has received her attention and thatthe desii-ed line designation is being recorded on her control circuit 18, Relay 11, upon enerv recorded in theV control circuit 18, ground isV removed at the control circuit from conductor 36 a-nd'relay 9 thereupon releases, discoi'inecting conductors 29 and 30 extending to the vcontrol circuit, trom the incoming end of trunk 5 and again connecting the incoming end of the trunk to the Windings of relay 6. Since the sender has now completed its functions, it now becomes disconnected from the district selector 2 and the callino' line, and the calling line becomes connected Withthe incoming end of the trunk circuit 5. Then relay 6 is again connected to the incoming end of the trunk circuit 5, it reenergizes and at its front contact, 'and the right inner Jfront contact of relay 11, establishes al holding circuit for relay 11 and :shunts the y winding of relay 23, whereupon relay 23 de- -energizes removing at its left contact the battery connection to the Winding of relay 9 and alsoy opening the initial energizing circuit o'f yrelay 11. 'At 4the outer right back contact of relay 23, a circuit is noW closed in shunt oit the disconnect lamp 38 extending through resistance 37, the .outer right back contact oi' relay 23 and the outer right front Contact of relay 11 vso that the lamp 38 will not light when theoperator inserts the plug 39 intojack 40. v v

The tandem home operator perceiving the complete number on her indicator, and noting that the oiiice designa-tion is `for a line terminating i-n manual oiiice Z, tests the jack 40 ot a trunk extending to such office by touching the tip of plug 39 to the sleeve of the jack. y

It the outgoing trunk is busy, she Will receive a busy clicl; in hc'r telephone circuit over a circuit which may be traced from the y tip ot vplug 39, through the upper vback contact of relay 41, conductor 42, outer right back contact of relay 33, conductor 43, through the tone coil of her telephone circuit (not shown) in the usual manner. If thev trunk is idle', as Will be assumed, she inserts the plug 39 into the jack 40, thereby closing a circuit from ground, through coil 44, slee-ve or" jack 40, sleeve of plug 39, Winding oi relay 41, thence in parallel to battery through the lamp 38 and the resistance `37.

Relay 41 operates in this circuit, but lamp 38 being shunted as above described does not light. Rel-ay 41 upon energizing, disconnects the test conductor 42 trom the tip oi' plug 39, and connects the tip of plug 39 to the tip conductor 48 of the trunk 5. Beforev the operation of relay 41, a shunt existed around the Winding oi' relay 35 from battery,

through the intermediate back contact of relay 41, intermediate normal contacts of relay .21

21 to battery through the Windingof relay 35. Upon the energization of relay 41, this lshunt is removed and relay 35 operates in a circuit from` battery through its Winding, intermediate contacts of relay 21, resistance 45 to ground at the `outer lett contact of relay 11.

Upon the operation of relay 41, a bridge is also establishedacross the tip and ring conductors 48 and 49 of the vtru-uli circuit extending from the tip of plug 39, upper t'ront contact of relay41, impedance coil 46, Winding of polarized relay 47, inner le'lft Contact ofrelay 11 to the ring Contact of plug 39, thus establishing a circuit eXtending to the oiiice Z for supervisory purposes.

r)The operation of relay 35 severs the tip and ring lconductors 48 and 49 of the calling end of the trunk circuit v5, from the incomving conductors 50 and 51 and connects conductors 48 and 49 through the upper and intermediate fron-t contacts of relay 35, inner left and right back contacts of relay 52 to the talking conductors extending to the home operators telephone circuit. The home operator may now converse With the B operator at 'the office Z, but the calling subscriber can-not hear :the conversation. The hom-e operator now gives the B operator Ethe number-ot the desired called line as indicated on the indicator and control circuit 18. Y

' After the tandem lhome operator has given the number, she depresses the Wipe-out key 53, thereby establishing a circuit for relay 21 `extending from battery, winding of relay 21, lower contact of relay 35, outer lett back contact ot' relay 52 to ground at key l53. Re-

oflice X and the terminating office Z. At'its left contact .relay 21. opens the holding circuitof relay 17 which now releases, in turn,

opening the circuit ofrelay 13. Relay 13 upon releasing opens the previously traced flashing circuit for lamp 14 and the lamp becomes dark. Y

In response to the instructions given to the B operator at office Z, the B operator in the wellknown manner extends the connection over plug 54 and jack 55 to the line of the desired subscriber. Upon the response of the called subscriber at station B,

apparatus at 100 functi-ons in the manner set forth in the above mentioned application, Serial No. 733,463, to reverse the direction of current owing through the polarized relay 47, whereupon relay 47 energizes closingl an obvious circuit for reversing relay 7. Relay 7 now reverses the d1rect1on of current flowing 1n the trunk extending to the originating office X for supervisory orf call charging purposes.

When the calling subscriber replaces his receiver on its switchhook, relay 6 releases in' turn releasing relay 11. Relay 11 upon releasing releases relay 21 and opens the circuit of relay 47. lith relay 11 deenergized the shunt around lamp 38 is removed and the lamp lights as a disconnect signal. Upon observing the lighting of lamp 38 the tandem operator removes the plug 39 from 'fs the jack 40`thereby releasing relay 41.

Relay 41, upon releasing, replaces the shunt around relay and extinguishes the lamp 33. When the relay 11 deenergized, the bridge through relay 47 and coil 46 is opened and the B7 operator at the ter1ninating office is given a disconnect signal in the usual manner and proceeds to take down vthe connection at her position. At the originating office the apparatus is restored in the manner fully set forth in the patent to Stearn 1,505,171 hereinbefore referred to.y

If at the time the call came in from the mechanical switching oiiice X, the home operator had been too busy with other calls to attend to such incoming call, the adjacent operator, if free, would have attended to it by depressing her display key 54. At this time relays 6 and 12 are operated as previously described and therefore upon the oper ation of key 54 a circuit is established for relay 55 extending from battery at the adjacent operators control circuit 56, over conductor 57, the outer right contact of relay` 'relayv23 and performs the other functions as previously described.

lilith relays 23 Vand 55 operated, a circuit is now closed extend- 'ing in parallel through the winding of relay 8 and the left winding of relay 33 which may be traced from ground at the adjacent operatorsl control circuit 56, conductor 60, outer left contact of relay 55, thence in parallel through the left winding of relay 33 and the winding of relay 3, conductor 26 to battery at the left contact of relay 23. Relay 8 upon energizing in this circuit, connects the incoming conductors of the trunk circuit 5 over conductors 61 and 62, to the adjacent operators control circuit 56, and opens the connection of the trunk circuit to the windings of relay 6. As before relay 6 deen'ergizes releasing relay 12 whereupon relay 11 energizes.

With relays 11 and 33 energized a circuit is now closed to lock relay 33 and to energize relay 52, this circuit extending from battery through the winding of relay 52 and the right winding of relay 33 in parallel through'the inner right Contact of relay 33, to ground at. the outer left contact of relay 11. Th-e circuit of lamp 14 is now transferred vfrom steady ground at the right contact of relay 12 to interrupted ground at the fast interrupter 59, over a circuit extending from battery through the lamp 14, resistance 15, the outer right back contact of relay 12, conductor 31, left front contact of relay 13, conductor 32, left front contact of relay 33 to ground through the interrupter 59. rllhe lamp 14 now flashes rapidly as an indication to the operators at both the home and adjacent positions, that the adjacent operator is attending to the incoming callon trunk 5.

lVhen the pulses have all been received and the indicator lamps associated with control circuit' 56 display the complete line designatiomcthe adjacent operator tests the trunk extending to the desired terminating oiiice Z, establishing a test circuit which may be traced from tip of plug 39, upperback contact of'relay 41, conductor '42, outer right front contact of relay 33, conductor 63 to the tone coil of the adjacentoperators telephone circuit (not shown). 'If the trunk tested is idle and the operator receives no click in her telephone circuit, she inserts plug 39 into jack 40. In response thereto, relays 41 and 35 operate as before. Since, however, relay 52 is now operated, relay 35 connects conductors 43 and 49 of the trunk circuit, through the inner left and right front contacts of relay 52 to the talking conductors of the adjacent operators telephone Hcircuit, to enable the operator at the adjacent position 1to conVerse with torvat oilice Z. Y A

To wipe outthe displayon the indicator ,and control circuit 56, thevadjacent operator depressesher wipe-out key 65 which closes a circuit for relay 21 'extending from bat tery through the Winding of 'relay 21, the

the B7 operalower .front contact of relay 35, ,the outer left front contact of relay 52, to ground through the contact of key 65. ,From this point, the circuits function in the manner previously described,

vVilliat is claimed is:

l. In a telephone system, a plurality of operators positions, a trunk circuit incoming to one of said positions and terminating in a plug, alt-rank signal, means at each operators position operable by the operator thereat in response to said signal, a telephone set at each operators position, and means automatically responsive to the insertion ot said plug into an outgoing line jack for disconnecting the talking conductors ot' said trunk circuit and tor connecting said plug to the telephone set of that operators position which has responded to said signal.

2. In a telephone system, a plurality of opeators positions, a trunk circuit incoming to one of said positions and terminating in a plug, an indicating device at each position, means at each position 'for associating the indicating .device of that position with said trunk circuit, a telephone set at each operators position, and means automatically responsive to the insertion of said plug into an outgoing line jack for disconnecting the talking conductors from said trunk circuit and for connecting` said plug to the telephone set of that operators position Whose indicating device is associated `u-.fith said trunk circuit.

3. .ln a telephone system, an operators position, a trunk circuit incoming to said position and terminating in a plug, a trunk signal, means controlled by the operator at said position in response to said signal, a telephone set at said position, a second operators position, means controlled by the operator at said second position in response to said signal, a telephone set at said second position, and means automatically responsive to the insertion of said plug into an outgoing line jack tor disconnecting the talking conductors of said trunk circuit and i'or connecting said plug to the telephone set ot that operators position which has responded to said signal.

Il. In a telephone system, an operators position, a trunk circuit incoming to said position and terminating in a plug, an indicating device at said position, means at said position for associating said indicating device with said trunk circuit, a telephone set at said position, a second operators position, an indicating device at said second position, means at said second position -lor associating said second indicating device with said trunk, a telephone set at said second position, and means automatically responsive to the insertion of said plug into an outgoing line jack for disconnecting Vthe talking conductors of said trunk circuit and for connecting said plug to the telephone set of that operators position Whose indicating device is associated with said trunk. Y j

5. In a telephone system, va plurality of operators positions, a trunk circuit incoming to one oi' said positions and terminating in a plug, a jack, a trunk signal, means at each operators position operable by the operator thereat in response to said signal, a telephone set at each operators position, a relay, means controlled by said relay vvhen said plug isplaced in said jack for disconnecting the talking conductors of sai-d trunk circuit and ifor connecting said plug to the ytelephone set of thaty operators position Ywhich has respondedto said signal, a key at each position, andfmeans responsive to the key of the connected position to disconnect the connected operators set and to reestablish the continuity of said trunk circuit.

6. In a telephone system, a plurality o'l operators positions, a trunk circuit incoming to one of said positions and terminating in a plug, an indicating device at each position, means at'each position for associating the indicating device of that position With said trunk circuit, a telephone set at each operators position, a jack, a relay, means controlled by said relay when said plug is placed in said jack for disconnecting` the talking conductors of said trunk circuit and for connecting said plug to the telephone set of that operators position Whose indicating device is associated With said trunk circuit, a key at each position, and means responsive to the key of the connected position to disconnect the connected operators set and to reestablish the continuity of said trunk circuit'.

7. ln a telephone system, a plurality oit operators positions, a trunk circuit incoming to one of said positions and terminating in a plug, an indicating device at each position, means at each position for associating the indicating device of that position with said trunk circuit, discriminating means responsive to said last named means, a telephone set at each operators position, and means automatically responsive to the insertion of said plug into an outgoing' line jack and to the operation of said discriminating means for disconnecting the talking conductors of said trunk circuit and for connecting said plug to the telephone set of that operators position Whose indicating device is associated with said trunk circuit.

8. In a telephone system, an operators position, a trunk circuit incoming to said position and terminating in a plug, a trunk signal, means controlled by the operator at said position in response to said signal, a telephone set at said position, a second position, means controlled by the operator at said second position in response to said signal, a telephone set at said second position, a listening in circuit, a transfer relay under control of one of said means for transferring said circuit 'from one telephone set to the other, and means automatically responsive to the insertion of said plug into an outgoing line jack for disconnecting the talking conductors of said trunk circuit and for connecting said plug to the listening in circuit.

9. In a telephone system, a plurality of operators positions, a trunk circuit incoming to one of said positions and terminating in a plug, an indicating device at each position, means at each position for associating the indicating device of that position with said trunk circuit, a telephone set at each operators position, a discrin'iinating relay responsive to said last named means, a second relay, means controlled by said second relay responsive to the insertion of said plug into an outgoing trunk jack for disconnecting the talking conductors of said trunk circuit and for connecting said plug through contacts of said discriminating relay to the telephone set of that operators position whose indicating device is associated with said trunk circuit, a key at each position, and means operable through contacts of said discriminating relay under control of the key of the connected position to disconnect the connected operator-s set and to reestablish the continuity of said trunk circuit.

In testimony whereof, I have signed my name to this specification this 23rd day of 35 February, 1926.

GEORGE H. PETERSON. 

